Hydrogen gas leak detection device

Abstract

To provide a hydrogen gas leak detection device that uses an orifice as a flow meter capable of measuring the flow rate of hydrogen gas in a high-pressure environment, and can easily detect hydrogen gas leakage from the flange of a pipe within an orifice assembly. [Solution] A hydrogen gas leak detection device comprising a hydrogen gas pipe for supplying high-pressure hydrogen gas, connected by a first flange 302 on the upstream pipe and a second flange 303 on the downstream pipe, wherein an orifice flow meter unit 30 is provided at the joint connecting the first flange 302 and the second flange 303, and an orifice plate 304 is sandwiched between them to measure the flow rate of hydrogen gas, and the orifice flow meter unit 30 provided at the joint measures the flow rate of the supplied high-pressure hydrogen gas and also detects high-pressure hydrogen gas leaking from the joint.

Description

Technical Field

[0001] The present invention relates to a method for detecting leakage from a flow meter, and more particularly to a hydrogen gas leakage detection device for detecting leakage of hydrogen gas during the process of supplying hydrogen fuel to a marine engine (diesel engine).

Background Art

[0002] In Patent Document 1, hydrogen gas stored in a gas tank is stored under compression at 100 MPa. However, when it is supplied to a hydrogen supply pipeline, for safety reasons, the hydrogen gas is supplied after being decompressed to less than 1 MPa. Even when the supply pipe of hydrogen gas is set to a low pressure of 0.2 MPa and a pipe thinner than a general hydrogen supply pipe is used, it is possible to transfer a sufficient amount of hydrogen gas required for consumption by a hydrogen-consuming device, and the flow rate at each location is measured, and leakage of hydrogen gas is detected from the inconsistency of the total sum.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the technique of Patent Document 1 has a problem that there is no disclosure of a device capable of measuring the flow rate of hydrogen gas in a high-pressure environment, that is, there is no flow meter approved by the High-Pressure Gas Safety Act. Furthermore, when measuring the flow rate using an orifice, even if there is a possibility of leakage of hydrogen gas in the flow meter, there is no method for grasping the leakage.

[0005] Therefore, the object of the present invention is to provide a hydrogen gas leak detection device that can easily detect hydrogen gas leakage from the flange of a pipe in an orifice assembly by using an orifice as a flow meter capable of measuring the flow rate of hydrogen gas in a high-pressure environment. Furthermore, other problems of the present invention will become clear from the following description. [Means for solving the problem]

[0006] The above problems are solved by the following inventions.

[0007] 1. The system includes a hydrogen gas piping that supplies high-pressure hydrogen gas, connected by a first flange on the upstream piping and a second flange on the downstream piping. An orifice flow meter unit is provided at the joint connecting the first flange and the second flange, which holds an orifice plate to measure the flow rate of the hydrogen gas. A hydrogen gas leak detection device characterized by having an orifice flow meter unit provided at the joint to measure the flow rate of the high-pressure hydrogen gas supplied, and a configuration to detect the high-pressure hydrogen gas leaking from the joint. 2. The hydrogen gas leak detection device according to claim 1, characterized in that the configuration for detecting the high-pressure hydrogen gas leaking from the joint comprises a leak port that guides the leaked hydrogen gas to a hydrogen gas sensor. 3. An annular opening for guiding the high-pressure hydrogen gas is formed at the end face of the flange. The hydrogen gas leak detection device according to claim 1, characterized in that the annular opening is connected to the tip opening of the leak port. 4. The hydrogen gas leak detection device according to claim 1, characterized in that the tip opening of the leak port is located outside the outer circumference of the orifice plate. [Effects of the Invention]

[0008] According to the present invention, a hydrogen gas leak detection device is provided that can easily detect hydrogen gas leakage from the flange of a pipe within an orifice assembly by using an orifice as a flow meter capable of measuring the flow rate of hydrogen gas in a high-pressure environment. [Brief explanation of the drawing]

[0009] [Figure 1] A diagram illustrating a method for supplying hydrogen fuel to marine engines (diesel engines). [Figure 2] Cross-sectional view showing an example of a hydrogen gas leak detection device according to the present invention. [Figure 3] Cross-sectional view of a key part showing an example of an orifice flow meter unit according to the present invention. [Modes for carrying out the invention]

[0010] Preferred embodiments of the present invention will be described below.

[0011] Figure 1 shows a method for supplying hydrogen fuel to a marine engine (e.g., a diesel engine), Figure 2 is a cross-sectional view showing an example of a hydrogen gas leak detection device according to the present invention, and Figure 3 is a cross-sectional view of a key part showing an example of an orifice flow meter unit according to the present invention.

[0012] In this invention, for example, the hydrogen fuel supplied to a marine engine such as a diesel engine is supplied as high-pressure hydrogen gas. High-pressure hydrogen gas can be obtained from liquid hydrogen, and the process can be carried out using the following three methods. The first method involves evaporating liquefied hydrogen stored in a liquefied hydrogen tank by raising the temperature in an evaporator without increasing the pressure to obtain hydrogen gas, storing this hydrogen gas in a hydrogen gas buffer tank, and compressing it using a gas compressor to obtain high-pressure hydrogen gas. The process of compressing the hydrogen gas with a gas compressor to increase its pressure can be performed from the hydrogen gas buffer tank to the orifice assembly. In the second method, high-pressure liquid hydrogen is obtained by a liquid hydrogen pump that compresses and increases the pressure of the liquid hydrogen stored in a liquid hydrogen tank. Next, there is a method of obtaining high-pressure hydrogen gas by vaporizing it regardless of the temperature in a vaporizer. In the third method, there is a method of obtaining boil-off gas generated from the liquefied hydrogen in a liquefied hydrogen tank without passing through an evaporator, storing it in a hydrogen gas buffer tank, compressing it using a gas compressor, and obtaining high-pressure hydrogen gas.

[0013] The first method is shown in FIG. 1. In FIG. 1, reference numeral 1 denotes a hydrogen gas buffer tank for storing hydrogen gas. In this embodiment, the liquefied hydrogen sent from a liquefied hydrogen tank (not shown) is sent to the hydrogen gas buffer tank 1 through an evaporator (not shown) that evaporates the liquefied hydrogen to obtain hydrogen gas. The hydrogen gas is sent from the hydrogen gas buffer tank 1 to the gas compressor 2 through the hydrogen gas pipe 10. The gas compressor 2 preferably adopts a multi-stage compression method. In this embodiment, it is composed of a front-stage compressor 20 and a rear-stage compressor 21.

[0014] The front-stage compressor 20 is not particularly limited, and a configuration that compresses in any number of stages, for example, 1 to 3 stages, can be adopted. The number of compression stages is not limited to a maximum of 3 stages. In the front-stage compressor 20, for example, it is compressed in the range of 0.6 to 19 MPa.

[0015] The rear-stage compressor 21 is not particularly limited as long as it can compress to meet the required pressure of a marine engine or an internal combustion engine. The rear-stage compressor 21 may further compress in 1 or 2 stages. In the rear-stage compressor 21, for example, it may be compressed to exceed 30 MPa.

[0016] The high-pressure hydrogen gas compressed by the gas compressor 2 is sent to the orifice assembly 3.

[0017] As shown in FIGS. 2 and 3, the orifice assembly 3 is composed of an orifice flowmeter unit 30, a first reducer unit 31, and a second reducer unit 32.

[0018] The first reducer unit 31 includes a reducer that expands a pipe with a smaller diameter than a hydrogen gas pipe with a predetermined diameter on the upstream side of the orifice flow meter unit 30 into a pipe with the same diameter as the hydrogen gas pipe. The second reducer unit 32 includes a reducer that reduces a pipe with the same diameter as a hydrogen gas pipe with a predetermined diameter into a pipe with a smaller diameter than the hydrogen gas pipe.

[0019] In the present invention, the reason for including the orifice flow meter unit 30, the first reducer unit 31, and the second reducer unit 32 in the orifice assembly 3 is that since it is a flange connection and there is a possibility of hydrogen leakage from the flange, it is preferable that leak ports for detecting hydrogen leaking from the flange are provided on those flanges.

[0020] Based on FIG. 3, the orifice flow meter unit 30 will be described. First flanges 302 and second flanges 303 are provided at the tips of the upstream pipe 300 and the downstream pipe 301 of the hydrogen gas pipe, respectively. The method of fixing the flanges to the pipe tips is preferably performed by welding.

[0021] In order to improve the strength, the hydrogen gas pipe of the present embodiment may be configured as a double pipe with a protective pipe provided on the outer periphery. Furthermore, it can not only improve the strength but also function as a protective pipe for preventing leaked hydrogen gas from the inner pipe from being exposed to the atmosphere.

[0022] The orifice plate 304 is mounted between the flanges 302 and 303. The thickness and hole diameter of the orifice are not particularly limited as long as it has a strength that can withstand high pressure.

[0023] Pressure sensing tubes 305 and 306 are attached to flanges 302 and 303, respectively. The method of attaching pressure sensing tubes 305 and 306 to flanges 302 and 303 is not particularly limited. It is preferable to select sensing tubes made of a material that can withstand gas pressure, and it is preferable to employ a sealing structure that prevents gas leakage. Pressure gauges 305A and 306A are provided at the tip ends of pressure sensing tubes 305 and 306. Pressure gauges 305A and 306A are connected to a control room (not shown) to which predetermined data is sent.

[0024] A leak port 307 is formed between the orifice plate 304 and the flange 302 to guide hydrogen gas to the outside if it leaks. This allows for immediate detection of hydrogen gas leakage from the orifice flow meter unit 30. The flange on which the leak port 307 is formed is not limited to flange 302, but may also be flange 303.

[0025] In this embodiment, the tip of the leak port 307 is open at the end face of the flange 302, and it is preferable that the flange 303 has an opening 308 for guiding the tip of the leak port 307. The opening 308 is formed in a cylindrical shape, and a part of this cylindrical shape is opened by the tip of the leak port 307, so that hydrogen gas leaking from the flange is easily guided to the leak port 307 regardless of which part of the opening 308 it leaks into. This makes it easy to guide the gas to the leak port 307 and allows for immediate detection of leaks.

[0026] As shown in Figure 3, it is preferable to provide sealing members 309A, 309B, and 309C above and below the radial opening of the tip of the leak port 307 (upper and lower perimeters). Sealing member 309A seals the space between flange 302 and orifice plate 304, and sealing member 309B seals the space between flange 303 and orifice plate 304. Sealing member 309C is provided on the outer circumference of the leak port 307 and seals the space between flanges 302 and 303. This is preferable from the viewpoint of reliably preventing hydrogen gas leakage from between flanges 302 and 303. O-rings and the like can be used as sealing members 309A, 309B, and 309C. The material is appropriately determined considering the gas pressure.

[0027] A hydrogen gas sensor 310 is provided at the tip of the leak port 307, which can detect leaking hydrogen.

[0028] To measure the hydrogen gas flow rate using the orifice plate 304, the hydrogen gas pressure on both sides of the orifice plate 304 is measured using pressure gauges 305A and 306A.

[0029] The hydrogen gas pressure at the inlet side of the orifice plate 304 is high, but the hydrogen gas pressure at the outlet side of the orifice plate 304 decreases due to pressure loss. The flow rate can be measured using a predetermined formula based on this pressure difference.

[0030] The following briefly describes the flow rate measurement method using the orifice flow meter unit 30. As shown in Figure 3, when a flow rate Q of hydrogen gas with density ρ is passed through an orifice plate, if the cross-sectional area A1 (inner diameter D), flow velocity v1, and pressure P1 are before throttling, and the cross-sectional area A2 (inner diameter d) (orifice), flow velocity v2, and pressure P2 are after throttling, the flow rate Q (cross-sectional area × flow velocity) can be calculated by the following formula (Equation 1). This makes it possible to accurately measure the flow rate under high pressure. This flow rate measurement allows for the determination of the supply amount relative to the demand of the internal combustion engine.

number

[0031] Next, we will describe the piping connection and hydrogen leak detection method using the first reducer unit 31 that constitutes the orifice assembly 3.

[0032] The first reducer unit 31 has a smaller diameter upstream pipe 311 than the hydrogen gas piping, and a downstream pipe (upstream pipe of the orifice flow meter unit) 300 with the same diameter, each end of which is provided with flanges 312 and 313. It is preferable that the flanges be fixed to the ends of the pipes by welding.

[0033] A leak port 314 is provided to detect hydrogen gas leakage from between the two flanges 312 and 313. In this embodiment, the leak port 314 is provided on flange 313, but it is not particularly limited and may also be provided on flange 312. A hydrogen gas sensor (not shown) is provided at the tip of the leak port 314.

[0034] Next, we will describe the piping connection and hydrogen leak detection method using the second reducer unit 32 that constitutes the orifice assembly 3.

[0035] The second reducer unit 32 has a downstream pipe 301 (downstream pipe of the orifice flow meter unit 30) with the same diameter as the hydrogen gas pipe, and a downstream pipe 321 with a smaller diameter, each of which is provided with flanges 322 and 323. It is preferable that the flanges be fixed to the ends of the pipes by welding.

[0036] A leak port 324 is provided to detect hydrogen gas leakage from between the two flanges 322 and 323. In this embodiment, the leak port 324 is provided on flange 322, but it is not limited to flange 323. A hydrogen gas sensor (not shown) is provided at the tip of the leak port 324.

[0037] Although embodiments of the present invention have been described above, the invention is not limited thereto. A clamp 33 may be provided before the first reducer unit 31, and a clamp 34 may be provided after the second reducer unit 32.

[0038] To prevent hydrogen gas leakage by keeping the hydrogen gas piping 10 of the orifice flow meter unit 30, the first reducer unit 31, and the second reducer unit 32 all horizontal, a suspension member 35 that supports from above to maintain a constant height and support members 36 and 37 that support from below are provided, as shown in Figure 2. This prevents rupture at the welded joints between the pipes and maintains a horizontal state. In this embodiment, clamps 33 and 34 are provided on both sides of the first reducer unit 31 and the second reducer unit 32, respectively, in order to reliably maintain a horizontal position and further prevent hydrogen gas leakage. [Explanation of Symbols]

[0039] 1. Hydrogen gas buffer tank 10 Hydrogen gas piping 2 Gas compressors 20 Low-pressure side compressor 21. High-pressure side compressor 3. Orifice Assembly 30 Orifice Flow Meter Unit 300 Upstream piping 301 Downstream piping 302 Flange 303 Flange 304 Orifice Plate 305, 306 Pressure sensing tubes 305A, 306A pressure gauge 307 Leakport 308 Opening 309A, 309B, 309C sealing members 310 Hydrogen gas sensor 31. First Reducer Unit 311 Upstream piping 312, 313 Flange 314 Leakport 32. Second Reducer Unit 321 Downstream piping 322, 323 Flange 324 Leakport 33, 34 Clamp 35 Suspension member 36, 37 Support members

Claims

1. The system includes a hydrogen gas piping that supplies high-pressure hydrogen gas, connected by a first flange on the upstream piping and a second flange on the downstream piping. An orifice flow meter unit is provided at the joint connecting the first flange and the second flange, which holds an orifice plate to measure the flow rate of the hydrogen gas. A hydrogen gas leak detection device characterized by having an orifice flow meter unit provided at the joint to measure the flow rate of the high-pressure hydrogen gas supplied, and a configuration to detect the high-pressure hydrogen gas leaking from the joint.

2. The hydrogen gas leak detection device according to claim 1 is characterized in that the configuration for detecting the high-pressure hydrogen gas leaking from the joint comprises a leak port that guides the leaked hydrogen gas to a hydrogen gas sensor.

3. An annular opening for guiding the high-pressure hydrogen gas is formed at the end face of the flange. The hydrogen gas leak detection device according to claim 1, characterized in that the annular opening is connected to the tip opening of the leak port.

4. The hydrogen gas leak detection device according to claim 1, characterized in that the tip opening of the leak port is located outside the outer circumference of the orifice plate.

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